Maybe we should verify the FFG vote target in p2p beacon_aggregate_and_proof screening

[lucianyao]

We don't verify the FFG vote target when screening message beacon_aggregate_and_proof, as we do when screening beacon_attestation_{subnet_id}:

[REJECT] The attestation's epoch matches its target -- i.e. 
attestation.data.target.epoch == compute_epoch_at_slot(attestation.data.slot)

[REJECT] The attestation's target block is an ancestor of the block named in the LMD vote -- i.e. 
get_ancestor(store, 
    attestation.data.beacon_block_root, 
    compute_start_slot_at_epoch(attestation.data.target.epoch)) == 
attestation.data.target.root

( also there is no verification in process_attestation, but I think it's not able to do it)

[dapplion]

The first condition is covered as of today

consensus-specs/specs/phase0/p2p-interface.md

Lines 361 to 362 in bf09b9a

	- _[REJECT]_ The aggregate attestation's epoch matches its target -- i.e. `aggregate.data.target.epoch ==
	compute_epoch_at_slot(aggregate.data.slot)`

For the second condition

• this PR supersedes it Align gossip validation for aggregates with single attestations #3552